1. Field of the Invention
This invention relates to artificial lens implants for the eye.
2. State of the Art
An intraocular lens (IOL) is an artificial lens implanted into the lens capsule of the eye in place of the natural crystalline lens of the eye because it has been clouded over by a cataract or injured. When the natural lens is removed from the lens capsule of the eye, lens epithelial cells (LECs) begin to multiply and spread on the posterior capsule and effectively render the posterior capsule opaque. This opacification, commonly referred to as posterior capsule opacification (PCO), causes clouding of vision and can lead to blurring and possibly total vision loss. While the LECs can theoretically spread on the anterior wall as well, due to the large opening in the anterior capsule (the capsulorrhexus), there is no wall for them to spread onto.
The occurrence of PCO is relatively high in traditional IOL implantations where the LECs spread between the IOL and the lens capsule. There have been some IOL designs where the sharpness of the corners of the lens has prevented cellular migration under the lens; however, recent literature suggests that these geometrical features simply retard the progression of PCO. PCO occurs in approximately 40% of IOL recipients within two years of receiving a synthetic lens.
The usual treatment for PCO is laser ablation of the posterior capsule where a laser is used to vaporize the posterior capsule and the cells that adhere to it. However, in terms of health economics, PCO is very expensive to treat. Therefore, it is desirable to avoid PCO at the outset.